基于摄影测量的拉索索力测试

发布时间：2018-06-26 00:44

本文选题：索力测试 + 摄影测量　；参考：《湖南大学》2015年硕士论文

【摘要】：拉索是索结构桥梁的主要传力构件,索结构的受力状态直接反映了全桥的健康状况,因此,需要对拉索进行持续索力监测。频率法凭借其方便、快速、可重复测试等特点在工程中得到了广泛的应用。但在某些特定条件下它们存在测量速度慢、工作繁琐、设备昂贵、难以考虑拉索边界条件等不足之处。针对以上问题,本文采用基于摄影测量和基于拉索模态振型进行索力识别,主要内容如下:(1)开展了基于运动目标图像跟踪法的拉索索力测试研究。在拉索上布置目标测点,用摄像机获取单个及多个目标的振动图像序列,利用背景差分法进行运动目标检测,基于卡尔曼滤波法对运动目标进行跟踪,获得拉索多个目标测点的振动位移时程曲线,进而利用频率法求解拉索索力。实验结果表明,与加速度传感器的结果相比,摄影测量法测试结果误差较小,是基于频率的拉索索力测试方法的有效发展与补充。(2)研究了基于摄影测量的拉索振动位移测量方法。用相机标定板作为参照物,通过相机成像平面上的点和标定板上点的坐标对应关系建立摄像机模型,从而建立二维图像与三维实体间的对应关系,求解相机的内、外部参数。进行了相机标定后,即能通过目标在图像上的位移推出它的实际位移。(3)研究了基于振型的拉索索力识别方法。这种方法通过选取拉索振动模态的两个驻点,将两个驻点之间的拉索等效为两端铰接的计算模型,根据两端铰接的拉索索力与振动频率的关系计算等效模型的索力,并将它近似视作原索索力。经过ANSYS仿真分析及实验室模拟初步验证了其精度和可行性。
[Abstract]:Cable is the main force transfer component of cable structure bridge. The stress state of cable structure directly reflects the health condition of the whole bridge. Therefore, it is necessary to monitor the cable force continuously. Frequency method has been widely used in engineering because of its convenience, speed and repeatability. However, in some special conditions, they have some shortcomings such as slow measurement speed, tedious work, expensive equipment, difficult to consider cable boundary conditions and so on. In order to solve the above problems, cable force identification based on photogrammetry and cable modal mode is adopted in this paper. The main contents are as follows: (1) the research of cable force testing based on moving object image tracking method is carried out. The measuring points are arranged on the cable, the vibration image sequences of single or multiple targets are obtained by the camera, the moving target is detected by background difference method, and the moving target is tracked based on Kalman filter. The vibration displacement time history curve of several target measuring points is obtained, and the cable force is solved by frequency method. The experimental results show that the error of photogrammetry is smaller than that of acceleration sensor. It is an effective development and supplement of cable force measurement method based on frequency. (2) the vibration displacement measurement method based on photogrammetry is studied. Using the camera calibration board as the reference, the camera model is established by the coordinate correspondence relationship between the points on the camera imaging plane and the points on the calibration board, and the corresponding relationship between the two-dimensional image and the three-dimensional entity is established, and the internal and external parameters of the camera are solved. After the camera is calibrated, the actual displacement of the target can be deduced by the displacement of the target on the image. (3) the method of cable force recognition based on vibration mode is studied. By selecting two static points of the vibration mode of the cable, the cable between the two points is equivalent to the calculation model of the two ends of the cable hinge, and the cable force of the equivalent model is calculated according to the relationship between the cable force and the vibration frequency of the two ends of the cable. It is approximately regarded as the original cable force. The accuracy and feasibility are preliminarily verified by ANSYS simulation and laboratory simulation.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446

【参考文献】